The basic adaptive filtering algorithm 

 is analyzed using the theory of weak convergence. Apart from some very special cases, the analysis is hard when done for each fixed 

 . But the weak convergence techniques are set up to provide much information for small 

 . The relevant facts from the theory are given. Define 

 by 

 on 

 . Then weak (distributional) convergence of 

 and of 

 is proved under very weak assumptions, where 

 as 

 . The normalized errors 

 are analyzed, where 

 is a "stable" point for the "mean" algorithm. The asymptotic properties of a projection algorithm are developed, where the 

 are truncated at each iteration, if they fall outside of a given set.